Decay property

The abundance of a trace element is often too small to be accurately quantihed using conventional analytical methods such as ion chromatography or mass spectrometry. It is possible, however, to precisely determine very low concentrations of a constituent by measuring its radioactive decay properties. In order to understand how U-Th series radionuclides can provide such low-level tracer information, a brief review of the basic principles of radioactive decay and the application of these radionuclides as geochronological tools is useful. " The U-Th decay series together consist of 36 radionuclides that are isotopes (same atomic number, Z, different atomic mass, M) of 10 distinct elements (Figure 1). Some of these are very short-lived (tj j 1 -nd are thus not directly useful as marine tracers. It is the other radioisotopes with half-lives greater than 1 day that are most useful and are the focus of this chapter. 

To render the KP theory feasible for many-body systems with N particles, we make the approximation of independent instantaneous normal mode (INM) coordinates [qx° 3N for a given configuration xo 3W [12, 13], Hence the multidimensional V effectively reduces to 3N one-dimensional potentials along each normal mode coordinate. Note that INM are naturally decoupled through the 2nd order Taylor expansion. The INM approximation has also been used elsewhere. This approximation is particularly suited for the KP theory because of the exponential decaying property of the Gaussian convolution integrals in Eq. (4-26). The total effective centroid potential for N nuclei can be simplified as ... 

Radical trapping studies, 14 277 Radicidation, 8 655 Radioactive decay, 21 287—288 particles associated with, 21 291 Radioactive decay properties of uranium isotopes, 25 393 Radioactive emission, interaction with tracer molecules, 21 276 Radioactive iodine, protection from,... 

The steady-state luminescence spectra of three different plastics are characterized by blue luminescence with Amax = 445-465 nm, while much broader liuninescence band with yellow color characterizes the dolomite rocks. These spectra are different, but not enough to differentiate between them from big distance. The decay properties have been also checked in order to improve the selective feature. It was found that luminescence intensity of rocks in the blue part of the spectrum is drastically diminished after specific delay time, while the decrease of intensity in the yellow part of the spectrum is mush more moderate. Liuninescence intensity of all plastics also diminishes after such delay, nevertheless remaining mush stronger then intensity of rocks luminescence in the blue part of the spectrum. The comparison of plastic and rock time-resolved spectra in specific time window clearly demonstrate that they are absolutely different, which made confident discrimination possible (Fig. 7.3). 

Table 1. Decay properties and availability of actinide isotopes for solid state studies ...

Table I. Generator Radionuclides for Labeling Cryptates Isotope Decay Properties Parent...

Glasses. Pearson and Peterson 98) studied extensively the fluorescent decay properties of terbium in Calibo base glass which has the composition CaO, 20 Li20, 10 B203, 70 mole per cent. All their data was taken using a stroboscopic method. 

Browne, E. and R. B. Firestone. Table of Radioactive Isotopes, Wiley, New York, 1986. An authoritative compilation of radioactive decay properties. Do note that the spontaneous fission half-lives are missing for several heavy nuclei. 

NUBASE Evaluation of Nuclear and Decay Properties, G. Audi, O. Bersillon, J. Blachot, and A.H. Wapstra, Nuclear Physics A729, 3 (2003). 

Audi, G Bersillon, O., Blachot, J. and Wapstra, A.H. (2003) The NUBASE evaluation of nuclear and decay properties. Nuclear Physics A, 729(1), 3-128. 

Positronium, being a readily available purely leptonic system and also a particle-antiparticle pair, has attracted considerable experimental interest over the years as a testing ground for the existence of exotic particles or couplings. The latter may perhaps manifest themselves in the decay properties of positronium, so that attempts have been made to observe forbidden modes. In particular, the longstanding discrepancy between the Michigan experimental value for oAo-ps and the results from QED calculations, described in subsection 7.1.1, has acted as a spur to such investigations. 

Clegg, L. J Coady, J. R., "Radioactive Decay Properties of CANDU fuel Volume 1. The Natural Uranium Fuel Cycle," AECL-4436/1, Chalk River, Ontario, Canada, 1977. 

In this section some of the E2 decay properties of the low-lying mixed symmetry band are discussed. In the IBA-2 model, E2 transitions are... 

In any discussion of decay data and their applications, the following should be kept in mind. In spite of their wide applicability, the primary motivation for their measurement has largely been the information which they provide for low-energy nuclear physics. The extensive measurement activity in this area over the past three decades or so has produced a large amount of fairly detailed data on the decay properties of unstable nuclei. 

Many of the applications, particularly the more challenging ones, of fission-product decay data have involved the fission products as a group. Because of their large number (>700) and the fact that almost no data have been available for many of them, it has always been necessary for such applications to utilize calculated values for the unmeasured quantities. To do this, a number of different approaches have been taken to describe the p-decay properties (p-strength functions) of these nuclides [TAK72,... 

Both theory and experiment, in close collaboration, are needed to refine the models used to calculate the p-decay properties of the individual nuclides. 

Thus, in order to understand such environments it is necessary to calculate complete network of the competitions between neutron capture and beta decay as well as their corrections for the thermal population of excited states. With regard to this latter correction it is particularly important to know the low-energy level structure of nuclei away from stability. This structure will affect the beta decay properties differently from the neutron capture properties. In a separate contribution to this conference, [TAK85] we will discuss the corrections for beta decay. Basically this becomes important if a low-lying excited state can undergo a Gamow-Teller allowed decay. The... 

Examples of large-basis shell-model calculations of Gamow-Teller 6-decay properties of specific interest in the astrophysical s-and r- processes are presented. Numerical results are given for i) the GT-matrix elements for the excited state decays of the unstable s-process nucleus "Tc and ii) the GT-strength function for the neutron-rich nucleus 130Cd, which lies on the r-process path. The results are discussed in conjunction with the astrophysics problems. 

More systematic calculations with the present method will certainly hel to clarify our understanding of the 0-decay properties of spherical nuclei fa off the line of stability, which are needed in r-process studies. In particular, a study of the effects of the 0-decay of low-lying states thermally populated in the high temperature r-process environment is due. Sue effects have not been included in any r-process model yet attempted. Finally we mention that a different approach (i.e. RPA) is probably called for in order to deal with deformed nuclei effectively [BRA85]. ... 

Identifying Nilsson States in A = 100 Nuclei by Investigating Gross /8-Decay Properties... 

Fig. 4. Levels of Zr and °Zr from (t,pYY) studies Levels are grouped according to their decay properties.

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